The invention concerns a balancing machine bearing mounting for flexible rotors in which the mountings are provided with bearing heads for the journals of the flexible rotors and a foundation to support such bearing heads.
Balancing machines for flexible rotors present a problem in that the natural frequencies of the unit consisting of the flexible rotor and bearing support are also dependent on the stiffness of the bearings in the balancing machine. Thus, it is desirable that the bearing stiffness be adjusted in the simplest possible manner within wide ranges.
For this purpose, a substantially rigid bearing mounting for a rotating body is known (U.S. Pat. No. 3,754,801) with support for each bearing location by means of a spring bar system located in a plane perpendicular to the main bearing axis. The overall system consists of spring bars, inflexible to tension, compression and buckling but consisting, in one or several sections, of spring bars which are flexible to bending and which secure the bearing housing against rotational movement around the main axis of the bearing and provide equally hard support against the machine base in all radial directions. On the other hand, this arrangement permits tumbling motions of the rotational axis of the rotating body around two axes, perpendicular to one another through the center point of the support location. An additional device is provided for purposes of tuning the oscillatory system of the test body plus bearing support, namely in such a form that additional supports are solidly anchored on one side, spring actuated and positively locked to the machine base, and connected at the other end to the bearing housing for intermittent tuning, namely via a friction connection, which can be remotely controlled and which obstructs the tumbling motions of the bearing housing as little as possible. Although such a bearing mounting for a balancing machine permits adjustment of the spring stiffness of the bearings, it is not suitable for direct reaction to the stresses emanating from the rotor to be investigated, even though, as is disclosed in this patent, a remote control is arranged for the friction connection that is provided. Nor is it suitable in order to obtain continuous selection of values for spring stiffness and damping.